um, you don't live around here, do ya?posted by quonsar at 8:45 AM on June 6, 2003

It's an interesting question. When species get too large and the population needs thinning out, in doing so we are having to choose a certain number as a standard. Of course, in reality, this standard is subject to change with the changing environment.posted by iamck at 8:54 AM on June 6, 2003

The problem with invasive species is that they are put into a new environment without any of their old predators and diseases. Therefore they thrive and they "outcompete" the native species because of an artificial advantage. This can throw the new ecosystem into chaos.

The first solution most people come up with is to introduce the diseases and predators of the invasive species in order to control the population. But this has led to many problems, because these diseases and predators can become invasive species themselves (without their predators and diseases). Follow this path far enough and you end up homogenizing all the environments.posted by Tallguy at 9:22 AM on June 6, 2003

A lot of the problem has to do with humans accelerating natural changes and at the same time wanting to control these natural changes. Exotic species naturally infest new areas on occasion, and when this happens it generally takes a very long time for the exosystem to reach some new sort of equilibrium. This is fine, and probably happened all the time in nature before humans began to have such a large influence. It's a cause for concern because these exotic species may change the ecosystem to one that we as humans may not be able to gain as much benefit from.

Sea Lampreys in Lake Erie are mainly a problem because they devastate fisheries. In this case, what does "nature" care wether Lake Erie is filled with lamreys or trout, when each would still probably constitute a healthy ecosystem.

So, are these invasions a part of the web called nature? Probably, yes. Do we need to control these critters? Also probably yes, to avoid depleted fisheries brought on by lampreys, or low-oxygen conditions indirectly brought on by Zebra mussels.posted by JumpW at 9:26 AM on June 6, 2003

in nature they wouldn't have gotten here in the first place, and if they had it would have been via millions of years of evolution and migration, in which natural checks and balances would have developed. as it is they have come by unnatural means into an ecosystem which has no defence against them. in order to keep what is left of an already badly damaged ecosystem alive it is necessary to at least get them under controlposted by renderthis at 9:26 AM on June 6, 2003

Humans are part of nature too. What makes tagging along on a ship less valid a method of spreading to a new area than, say, tagging along on a piece of driftwood?posted by beth at 9:38 AM on June 6, 2003

Nature finds a way, sure, but these things would not have happened without us - so it's not exactly natural. We are one of the newest species on this planet, remember.posted by agregoli at 9:54 AM on June 6, 2003

(rant)
Really in the end this all comes down to an issues of values: if you value a crystal clear lake with no fish, a bunch of mudsnails, some crawdads, and massively clogged power-station and sewage treatments inputs coasting hundreds of millions of dollars per yer, then, well, hey- go go invasives.

If you want an environment where every inch of space underwater is covered by massive colonies of crazy tunicates and other things, preempting the space needed by algae and other food sources for the fish, crabs, and more which we in turn then depend on for food, so be it.

If you want the Colorado river dried up by a wide variety of invasives which use more water and raise the salt table so that other species cannot grow around the river banks, if you want hundreds of bird species to have no roosting place, want to have to use increasingly harsh chemicals on your food so that invasive bugs and plants can't decimate them, well, more power too you.

If you don't mind a massive homogenization of the life on this planet such that a few newly evolved plant diseases or some such only have to undergo a few hundred mutations to be able to infect everything on the planet rather than billions, have fun!

Beth, a mussel larvae attaching to a piece of driftwood will move down a river a few hundred kilometers at most. A mussel larvae being sucked into a new high speed cargo transport which, previous to 20 years ago, simply didn't exist, will move across continents. The biota on this planet simply didn't evolve under conditions where such things were possible. If you want the entire biota of the planet to shift radically, altering and perhaps eliminating all of the ecosystem services mankind has come to value throughout its own existence on this earth, well, there's really nothing I can say to convince you. It's going to be a hell of a ride, though, and one I don't want my children and their children to be a part of, as it will suck mightily.

Granted, I've somewhat overstated my case. Although looking at just the zebra mussels, tamarisk, a new invading tunicate that has spread around the world in 2 years, and more, sometimes I wonder if the above just may come to pass.... take a look at invasivespecies.gov as a nice starting point to explore what's going on in the world of invasives. It's quite scary.

That's quite the piece of driftwood that could float _up_ the St. Lawrence...posted by Space Coyote at 10:03 AM on June 6, 2003

We are one of the newest species on this planet, remember.

agrecoli -- How so? We didn't come from another planet, did we?

I've always believed that humans are a part of nature, and thus the changes we make to our environment are natural as well. Big buildings are as much a part of the natural environment as beehives, when you think about it. So it seems to me that species introductions to the Lakes via shipping in the Seaway is, well, nature finding a way, as you put it.

on preview: jearbear has a point, and I stole it. Oops.

Not that I'm all for invasives; personally, I think we should be concerned about them. Having fisheries decimated by lampreys or zebra mussels costing millions of dollars in damage to power stations and treatment facilities is definitely a cause for concern, to put it mildly.

But then again, I'm not a marine biologist, so what the hell do I know?posted by Jughead at 10:09 AM on June 6, 2003

On the one hand, it's a real problem.

On the other hand, it would be cool if there were kangaroos out in the great plains. Especially if they were being chased by deinonychus or smilodon.posted by ROU_Xenophobe at 10:12 AM on June 6, 2003

An interesting thing to consider is how to deal with endangered species in this kind of dynamic. In reality, you could examine all the endangered species, and think about relocating populations of them. Think of taking all those marsupials in Australia and making populations in similar zomes throughout the world.

Maybe one 'pest' invader from one part of the world can be better controlled, not by its natural predator, but by another species from someone else.

Hey - can bamboo survive in a natural environment outside of China? If so, create a forest and transplant some panda bears.

I don't see the hoopla over trying to preserve someplace exactly how it is. Though, I do understand wnating to preserve a bio-diversity that works. Sea lampreys by themselves in the Great Lakes don't work because there is no control. They are not a 'top of the pyramid' predator (one reason why they have such active reproduction).. top predators typically have fewer offspring that varies with living conditions and the environment.

So, when you have a not-top predator at the top with no controls, they quickly destroy the whole chain, resulting in a dead zone instead of any kind of biological enviornment.posted by rich at 10:23 AM on June 6, 2003

The problem with invasive species is that they are put into a new environment without any of their old predators and diseases. Therefore they thrive and they "outcompete" the native species because of an artificial advantage.

It really comes down to idosyncracies in the environment that the species is introduced to whether it becomes a problem, not such a sure thing as you think. Many ecosystems are robust enough to resist invaders, this strength usually as a function of diversity. The gravity of the weakness exposed by slowly thinning the number of species by habitat destruction and invasives can then be realized. On the other hand, an invasive could be really beneficial (for the interations of the ecosystem, or humans), the problem with God-type human interventions being we really just dont understand the chaotic interactions of life well enough to decide.

The biota on this planet simply didn't evolve under conditions where such things were possible.

Hawaii is a case in point where "invasives" successively colonized the islands from jumping points in Asia, the South Pacific, and North America. Admittedly their only (pre-Polynesian) mammals were bats, but a wide diversity of fish, plants, and birds arrived. (Aside - Hawaiian berry plants devolved thorns after reaching the islands, an evolutionary tidbit I just think is cool)

It is likely that major migrations, and the resulting extinctions have occurred many times in the past. The difference is the rate at which we modern humans are spreading the new species, bsaically just multiplying the problem. Whereas the Bering land bridge opened up say 8 times in the last few milliion years, a cargo ship comes on the order of a billion times more often than that.

Invasives aren't just a nuisance to humans; as you said later jearbear the resistance to disease is lowered, endangering a greater range of habitats. We are undergoing on of the top 10 (low estimate) major extinctions of geologic time right now (K-T is around 4th). Its a natrual experiement in ecology that I'm just afraid of.posted by copmuter at 10:42 AM on June 6, 2003

From this old article, it seems that Sea Lampreys are a delicacy. Maybe we should use the lessons learned from the Atlantic Canada fisheries and eat them into extinction?posted by titboy at 10:51 AM on June 6, 2003

Well, hey, titboy, the invasive asian tunicate, Styele Clava is a delicacy in Korea - $5/lb. And last year, Canadian mussel farmers threw away roughly 50 tonnes from their mussel lines. Mussel go from $2-3/lb....hrm... methinks there's a profit to be made.

Of course, this kind of thing can backfire. Just look at the enormous market and PROTECTION now enjoyed by the invasive Russian Red King Crab in Norway.posted by jearbear at 11:03 AM on June 6, 2003

Well hell, the Great Lakes were ridiculously polluted and the water quality was dismal before the zebra mussels arrived. True, they clog the shit out of the lake, but as filter feeders, they've single-handedly cleaned up the water there. Now the silt is still very bad news, but you can actually eat some of the Great Lakes' fish again... just not bottom feeders.

And, you can snorkle and actually see things, now. 15 years ago the visibility was maybe a foot... today, the water is fairly clear and you can see 10 to 15 feet on a good day.

The zebra mussel gets a bad rap from the industries that have to pay to unclog their pipes, but I would say it's done more good than harm.posted by BobFrapples at 11:29 AM on June 6, 2003

It's just like newbies on MetaFilt--OW!

Actually, there's a really good book on unintended consequences in the technological age. There's an interesting section on species that were introduced into their non-native environments for one reason or another, and the effects thereof. (Kudzu was introduced into the South from Japan for erosion-control purposes...it now chokes the region. Same deal with multiflora rose in West Virginia.)posted by Vidiot at 11:29 AM on June 6, 2003

So, we humans , too, are one of these invading species?posted by cookie-k at 11:48 AM on June 6, 2003

The question can't be one of preservation rather one of conservation. We need to setup refuges where native species can thrive, and this is being done. But the idea of stopping invasive species entirely is impossible we just have to hope for the best and not kill the rest.posted by stbalbach at 11:51 AM on June 6, 2003

We need to setup refuges where native species can thrive

Setting them up isn't enough. Invasive exotic plant species (here in FL, melaleuca and Brazilian Pepper are prime examples) can spread rapidly by wind, birds, or whatever and can quickly invade almost any native habitat. Vast areas of the Everglades and surrounding areas have been completely taken over by melaleuca, which forms a dense monoculture that crowds out every other plant. Literally. A stand of this stuff makes a commercial tree farm look like an old growth forest.

In some cases, it actually is better to try and wipe the invader out over the long haul, rather than try to selectively protect certain areas from these pests in the general environment.

No offense meant to invasive Metalfilter pests, alien or otherwise...posted by groundhog at 7:46 PM on June 6, 2003

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